It's late, so I'll just answer a couple (I don't know the answers to
all of them anyway) of your questions.

You turn the player on by holding the top button. You only need to
add the middle one if you need to reset or switch back to Rockbox
after using the Apple firmware. Hold down the bottom of the wheel
for four seconds to turn it off. That's how it works on the Nano; it
might be a bit different with the Video.

You can check battery status and the time by going to the main menu,
choosing Info, then Rockbox Info. I'm not sure how you set the time, though.

You can switch back and forth between the file browser and database
at any time. I haven't used the database because it doesn't work
with the MP3 clips; I think it spells everything.

When you open a folder and play a track, a playlist of all the tracks
in that folder is automatically created. So if they're all the
tracks from an album, and they're numbered in order, the entire album
will play in order. When you switch to a different folder, the first
playlist is discarded and one is created for the new folder. You can
create other playlists if you want and can save them, but you don't have to.